Power management for computers began as a way to extend the “between-charges” operating time of a battery-powered (e.g., laptop) computers. More recently, the demand for power by large computer systems has grown to the point that it is a substantial factor in total cost of ownership. Some large computer installations, e.g., data centers, can strain the ability of a power utility company to deliver the power. Accordingly, power management is now used to maintain power consumption within energy-conservation and economic budgets.
Computers manipulate data stored in computer-readable media in accordance with programs of computer-executable instructions, also encoded in computer-readable media. Application programs running on the computer define the mission of a computer. Rather than running on hardware, applications run on a mission operating system that provides an interface between the applications and the hardware-relieving application developers of the need to ensure compatibility with each hardware variant on which the application is to run. The operating system communicates with the hardware through a “hardware abstraction layer” (HAL) or “basic input-output system” (BIOS), which launches automatically when the computer is powered on, initializes devices, launches the operating system, and serves as an interface between the operating system and hardware.
An “advanced power management” (APM) specification assigns control of power to the HAL, with limited intervention by the operating system. In an “Advanced Configuration and Power Interface” (ACPI) model, the HAL provides the OS with methods for directly controlling the low-level details of the hardware so it has nearly complete control over the power savings. For example, systems may be put into extremely low-consumption states, from which the system can be awaked by ordinary interrupts (real time clock, keyboard, modem, etc.).
Having the operating system control power settings allows power settings to be readily tailored to the needs of application programs running on the operating system. However, in large multi-server installations in which several different operating systems can be running on a common hardware platform, the role of an information-technology administrator in controlling power is complicated by the fact that each operating system has its own user interface and methods of controlling power. What is needed is a way to allow a consistent user interface across operating systems while retaining the flexibility offered by operating-system control of power settings.
Herein, related art is described to facilitate understanding of the invention. Related art labeled “prior art” is admitted prior art; related art not labeled “prior art” is not admitted prior art.